basic_string allocator

[Syslock]

Can someone point me to an example of a custom std::basic_string allocator that compiles under VS 2005 or VS 2008?

I can't get this code to compile. All errors refer to a file called xstring. The following code might have worked
under MSVC++ 6.0, but apparently something has changed in basic_string since then.

#include <string>

template<class T>
struct MyAllocator {

 typedef T* pointer; 
 typedef const T* const_pointer; 
 typedef T& reference; 
 typedef const T& const_reference; 
 typedef T value_type; 
 typedef size_t size_type; 
 typedef ptrdiff_t difference_type;

 pointer address(reference x) const { return (&x); } 
 const_pointer address(const_reference x) const { return (&x); } 

 pointer allocate(size_type n, const_pointer = 0) {
    return (pointer)::operator new(n * sizeof(T));
 }
  void deallocate(pointer p, size_type n) {
    ::operator delete(p);
 }
};


typedef std::basic_string<char, std::char_traits<char>, MyAllocator<char> > MyString;


int
main(int argc, char *argv[], char *env[]) {

 MyString str;

 return 0;
}

C:\Program Files\Microsoft Visual Studio 8\VC\include\xstring(467) : error C2903: 'rebind' : symbol is neither a class template nor a function template
        C:\Program Files\Microsoft Visual Studio 8\VC\include\xstring(496) : see reference to class template instantiation 'std::_String_val<_Ty,_Alloc>' being compiled
        with
        [
            _Ty=char,
            _Alloc=MyAllocator<char>
        ]
        ..\main.cpp(37) : see reference to class template instantiation 'std::basic_string<_Elem,_Traits,_Ax>' being compiled
        with
        [
            _Elem=char,
            _Traits=std::char_traits<char>,
            _Ax=MyAllocator<char>
        ]
C:\Program Files\Microsoft Visual Studio 8\VC\include\xstring(467) : error C2039: 'rebind' : is not a member of 'MyAllocator<T>'
        with
        [
            T=char
        ]
 etc...

[Paul McKenzie]

First, Visual C++ 6.0 is not an ANSI compliant C++ compiler -- many things that compile there will not compile using an ANSI compliant compiler.

An ANSI compliant C++ compiler requires that the basic_string allocator have a rebind() function defined.

Can someone point me to an example of a custom std::basic_string allocator that compiles under VS 2005 or VS 2008?

MSDN?

http://msdn.microsoft.com/en-us/libr...8VS.80%29.aspx

Regards,

Paul McKenzie

[Syslock]

Thanks, I just had to add one line:

 template <typename U> struct rebind { typedef MyAllocator<U> other; };

and it compiled! Awesome.